The heists lead to other heists in a branching way. You can repeat heists in different ways.

I have played a few of the heists and it seems like you can go quietly and wait for people to turn their back while you sneak around or you can go right in and whip out the guns and stick up the place. Those are the extremes, you can make a middle ground if you want.

I hope that helps!

I will say linear, there is no "random event" as in payday.

But as Nimras says, there is 4 branches story and various tactic for each heists.

When you are a "pro", you can do this game in 4 hours... but you will need at least 2 weeks to play it good enough...

Is there a "career mode" or sandbox gameplay, do I have to play heists in predetermined order? Recruit who I want?

It is somewhat of a sandbox gameplay but in order to progress through the heists you need to go to each heist and find the Item and bring it back to hideout to progress.

It is a random name gang store, you can change it by going to a heist and go back to the hideout and repeat.

....it is a career mode game. The heists are mostly in a predetermined order. You can recruit anyone you want....but they are not all visible at once.